An intake manifold is connected to an internal combustion engine mounted on a vehicle. The intake manifold includes a surge tank and intake branch pipes. The intake branch pipes distribute intake air to cylinders of the internal combustion engine. Because the intake manifold has a complex shape, the intake manifold is formed of a plurality of split pieces that are connected to each other via joint faces.
Fuel injection valves are provided in the internal combustion engine. It is required to suppress a collision of the intake manifold with the fuel injection valves at the time of a collision of the vehicle.
As a technique for suppressing a collision of an intake manifold with fuel-system components, there is a technique that the distance between a delivery pipe and a position at which an intake manifold upper of an intake manifold and an intake manifold middle of the intake manifold are welded to each other is ensured at or above a predetermined distance a (for example, see Patent Document 1). This intake manifold is able to prevent damage to the delivery pipe due to a broken piece of the intake manifold when the intake manifold is damaged at the time of a collision of a vehicle.